INSTRUMENTS AND METHODS. 



19 



Nearly all the sledging thermometers (spirit) were provided with minimum indices, and 

 after the sledge had been straightened for the night the open thermometer was carefully 

 placed under the sledge in such a position that it was shielded from radiation. There is 

 little doubt that a thermometer so placed gave minimum temperatures too low by a degree 

 or tw'o, but it will be shown that the minimum temperatures are of great value and cannot 

 be neglected in obtaining the mean temperatuie for the day. The daily range of the tem- 

 perature on the Barrier is so great that the mean temperatures cannot be obtained rom 

 simple temperature observations taken two or three times a day, for the time at which the 

 observations are taken makes a very large difference in the temperatures recorded. The 

 following example will illustrate this and will serve to show how the mean temperatures 

 on the Barrier were obtained. 



During the main southern journey temperature observations were taken by Bowers and 

 Meares. The former marched with the ponies and the latter travelled with the dogs. During 

 the greater part of the journey, the ponies marched at night and rested during the day. 

 In consequence the observations were generally taken by Bowers as follows : — 



(«,) When the march .started at about 9 p.m. 



(h) At the mid-march halt at about 3 a.m. 



(c) When the march ended at about 10 a.m. 



Owing to the fact that the dogs did the same march as the ponies in a very short 

 time and without any break, the times for observing used by Bowers were not convenient 

 to Meares. The latter, thcrefoie, made his observations at (a) 4 a.m., (b) 8 a.m., and 

 (c) 4 p.m. approximately. 



The following table gives the two sets of observations for a short period of four days: — 



Table 3. 



Each ot the observers took observations three times a day and yet the mean tenipoia- 

 tures shown by the observations differs by nearly 8 degrees. The reason is at once apparent 



